Apparatus for manufacture of filamentary material by wet spinning



1950 R. J. BROWN mm.

7 APPARATUS FOR MANUFACTURE OF FILAMENTARY MATERIAL BY WET SPINNING Filed Feb. 17. 1955 ONT 7 l w 1 row tats APPARATUS FOR MANUFACTURE OF FILANIEN- TARY MATERIAL BY WET SPINNING Russell Jacques Brown and John Downing, Spondon, near Derby, England, assignors to British CelaneseLlmlted, a corporation of-Great Britain Filed Feb. 17, 1955, Ser. No. 488,868

Claims priority, application Great Britain Feb. 23, 1954 2 (Ilaims. (Cl. 18-8) This invention relates to the manufacture of filamentary material by wet-spinning processes.

-In one method of making artificial filamentary material by wet-spinning, especially material having a high tenacity, theextruded filaments and the coagulant travel upwardly through a vertical narrow tube. Such a process is described in US. applications Ser. Nos. 323,788, filed 'De- *cember 3, 1952, and 451,191, now abandoned, filed August 20, 1954. Preferably the filaments are drawn from the tube at a rate such that they are stretched to a considerableextent before they are 'fully set, and it is important that the flow of coagulant through the tube should be as uniform as possible, so as to avoid subjecting the filaments while they are still soft to varying tensions, which give rise to variations in the degree of stretch and thus in the physical properties and denier of the filaments.

One difliculty that arises in wet-spinning processes of this kind is a tendency to the occurrence in the :product of broken filaments; this difficulty is particularly pro- 'tain a very uniform product, apparently because the use of the apparatus makes it easier to achieve substantially streamline and non-turbulent flow in the coagulant, especially in the immediate vicinity of the spinning jet.

The apparatus of the invention comprises a closed vertical outer tube, a coaxial narrower inner tubeopening into the outer tube at a level substantially above the lower end of the outer tube and extending upwards beyond the upper end thereof, an upwardly facing spinning jet in the outer tube below and coaxial with the inner tube, means for feeding a spinning solution to the spinning jet, means for introducing coagulant into the upper end of the outer tube, and means for collecting coagulant from the upper end of the inner tube. Advantageously, the inner tube is centered in the outer tube by means of vertical fins at or near its lower end, and these fins then serve also to diminish or prevent possible turbulence in the coagulant as it approaches thespinningjet. It is also of advantage to provide a perforated screen, eg a wire mesh or gauze, across the space between the two tubes and near the upper end of the outer tube to promote streamline flow of the coagulant down the said space.

In the further description of the invention, it will be convenient to refer to that part of the outer tube which extends below the lower end of the inner tube and which contains the spinning jet as the extrusion chamber, and to the inner tube as the setting tube; the use of the 2,959,813 Patented Nov. 15, 1960 .2 term setting tube does not however imply that the whole operation of setting, i.e. the conversion ofthe extruded streams of viscous spinning solution into filaments having only very slight plasticity at ordinary temperatures, necessarily takes place in the inner tube.

The lower end of the setting tube is preferably flared outwardly, so as to promote a smooth flow of coagulant into the tube. Apart from this, the diameter of the setting tube may be constant throughout its length, or it may decrease in one or more small steps, for example as described in US. application Ser. No. 451,191, now abandoned, filed August 20, 1954, it is in any case preferable that the setting tube should be constricted at its upper end, if only over a distance so short as to form in effect merely a small constricted orifice.

The optimum diameter of the setting tube depends primarily on the number of filaments and total denier of the material being spun; for example, it may range from about 0.15 to 0.25 inch when spinning low denier material containing relatively few filaments, to about 0.5 to 0.6 inch or more when spinning high denier material for conversion into staplefibre, e.g. material of denier between about 2000 and 3000 containing about 1250-2000 filaments. The diameter of the outer tube should be at least twice, and is preferably at least 2.5 or 3 times the diameter of the setting tube. We prefer to employ an outer tube of diameter such that the linear speed of the coagulant flowing down the annular space between the two tubes is below 1 metre per minute and especially between about 0.1 and 0.75 metre per minute. 7

It will be apparent that, when the apparatus is in use an annular stream of coagulant issues from the annular space between the two tubes into the extrusion chamber, and there changes its form and direction, becoming a stream of more or less circular cross-section flowing up the centre of the extrusion chamber from the neighbourhood of the jet into the setting tube. In order to cause this change of form and direction to proceed smoothly, it is advisable to insert a'deflector plate in the extrusion chamber at about the level of the jet. A very useful form of deflector plate consists of an annular plate having its upper surface concave, which surrounds the 'jet and extends nearly or quite into contact with the wall of the outer tube. Such an annular deflector plate can conveniently rest on the jet mounting, so that its inner edge is a little below, and its outer edge preferably a little above, the level of the jet face.

A form of apparatus in accordance with the invention is illustrated diagrammatically in the accompanying drawing, in which the 'figure is a sectional elevation of the apparatus.

Referring now to the drawing, the apparatus comprises a vertical outer tube 1 provided at its upper end with a closure 2. through which pass an inlet pipe 3 for coagulant, an air vent i, and an inner orsetting tube 5. a i

The lower end of the setting tube 5 is some distance above the bottom of the outer tube 1, and is flared outwardly.

The upper part of the setting tube 5 extends above the closure 2, and at its end is narrowed to form a constricted orifice 6. Surrounding the upper end of the setting tube is a gutter 7 provided with a run-off 3 for coagulant -leav-' ing the setting tube. The lower end 9 of the outer'tube 1 is closed, and through it passes a feed pipe 10 leading ried by the setting tube 5 near its lower end serve both to keep the setting tube accurately in positon and also to smooth the flow of coagulant down the annular space between the outer tube and the setting tube. An annular metal gauze 16 extends across the said annular space towards the upper end of the outer tube.

In operation, the air vent 4 is at first kept open, and coagulant fed in through the inlet pipe 3 until it completely fills the annular space between the outer tube 1 and the setting tube 5, the lower part of the outer tube 1 which forms the extrusion chamber, and the setting tube to the level of the closure 2. The air vent 4 is then closed by means of a tap (not shown), and a stream of coagulant is fed continuously through the inlet pipe 3, down the annular space between the outer tube 1 and the setting tube 5, and so into the extrusion chamber and up the setting tube, at the top of which it overflows into the gutter 7, whence it flows away through the run-oft 8 to a suitable recovery unit. A spinning solution is now fed under pressure to the jet 11 in the known way, and passes through the jet holes to form filaments which are set and carried up the setting tube by means of the coagulant. The filaments are passed round a godet (not shown) by means of which they are drawn from the setting tube at a speed considerably higher than the linear extrusion speed, so stretching them.

The wet-spinning apparatus of the invention may be used in conjunction with any suitable ancillary devices acting on the filamentary material produced. Thus it is advantageous to provide some means for removing adherent coagulant from the material shortly after it has left the setting tube and before it reaches the godet employed to draw it through and out of the tube. Such means for removing adherent coagulant may comprise a simple yarn guide, such as a pigtail guide, but we prefer to use an inverted closely spaced conical wire spiral, as described in U.S. application Ser. No. 457,721, now Patent No. 2,852,808, filed August 22, 1954, or a device comprising an inverted funnel as described in U.S. ap plication Ser. No. 451,190 now patent No. 2,911,674, filed August 20, 1954. Another useful device that may be used is described in U.S. application Ser. No. 499,166, now Patent No. 2,895,790, filed April 4, 1955, and comprises a driven or free-running roller which is preferably caused to rotate at a peripheral speed a little lower than that of the godet, and is so positioned that the filamentary material makes contact with it over a small are before reaching the godet. The godet employed to draw the material through and out of the setting tube may comprise a cylindrical roller, 21 fluted roller or the like as described in U.S. application Ser. No. 451,193, now abandoned, filed August 20, 1954or a number of yarncarrying bars arranged approximately in the form of a cylinder, as described in U.S. application Ser. No. 451,192, now abandoned, filed August 20, 1954. It is usually desirable that the material should make two or more turns round the godet, and it is then advantageous to provide a skew idler roller or other means whereby the turns are kept separate. From the godet the material passes to one or more washing devices, comprising for example a pair of thread-advancing rollers one or both of which is partly immersed in a bath of washing liquid, for instance as described in U.S. application Ser. No. 323,788, filed December 3, 1952, or in U.S. application Ser. No. 457,684, now abandoned, filed September 22, 1954.

The use of the wet-spinning apparatus of the invention is illustrated by the following example.

Example A device as shown in the drawing was employed, having the following dimensions: Internal diameter of setting tube inches 0.5 Length of setting tube do 42 Diameter of orifice at the upper end of the setting tube inches 0.24 Spinning jet-4500 holes of diameter mm 0.10

Diameter of outer tube (inches) 1.62 2. 5 3. 0 Width of annular space (inches) O. 24 1. 0 1. 2 Linear speed of coagulant through annul ace (metres/minute) 6. 0 0.8 0. 6 Tenacity of product (grams/den.) 2. 2 2. 0 2. 2 Extensibility of product (percent) 15 15 15 Filament breaks per gram of product 10 7 The apparatus of the invention may be employed with advantage in a wide variety of wet-spinning operations, including the spinning of acetone solutions of cellulose acetate using as the coagulant aqueous diethylene glycol diacetate or aqueous acetone, and the spinning of acetic acid solutions of cellulose acetate using as the coagulant aqueous acetic acid, which may contain an alkali metal acetate or other salt. The apparatus may also be used in wet-spinning other cellulose esters and cellulose ethers, ejg. cellulose esters of propionic and butyric acids and alkyl and aryl celluloses, viscose, and other organic fil-v ament-forming substances including polyvinyl alcohol, copolymers of vinyl acetate and vinyl chloride, polyacrylonitrile and copolymers of acrylonitrile with other vinyl compounds or with vinylidene chloride.

Having described our invention what we desire to secure by Letters Patent is:

1. Apparatus for the manufacture of artificial filamentary material by a wet spinning method, which comprises a fixed closed vertical outer tube, a fixed coaxial narrower inner tube having near its lower end vertical fins extending to the outer tube and serving to centre it in the outer tube, said inner tube being constricted at its upper end and flared outwardly at its lower end and opening into the outer tube at a level substantially above the lower end of the outer tube and extending upwards beyond the upper end thereof, the arrangement being such that liquid can flow downwardly through the annular space between the two tubes in a substantially streamline manner, the diameter of the outer tube being at least three times that of the inner tube, an upwardly facing spinning jet fixed below and coaxial with the inner tube, a fixed annular deflector plate having its upper surface concave, its outer edge in contact with the wall of the outer tube at a level above that of the spinning jet, and its inner edge surrounding and in contact with the periphery of the spinning jet, means for feeding a spinning solution to the spinning jet, means for continuously introducing coagulant into the upper end of the outer tube at a volumetric rate such that the linear speed of coagulant between said tubes is less than about 1 meter per minute and means for continuously collecting coagulant from the upper'end of the inner tube.

2. Apparatus for the manufacture of artificial filamentary material by a wet spinning method, which comprises a fixed closed vertical outer tube, a fixed coaxial narrower inner tube having near its lower end vertical fins extending to the outer tube and serving to centre it in the outer tube, said inner tube opening into the outer tube at a level substantially above the lower end of the plate having its upper surface concave, its outer edge in contact with the wall of the outer tube at a level above that of the spinning jet, and its inner edge surrounding and in contact With the periphery of the spinning jet, means for feeding a spinning solution to the spinning 5 jet, means for continuously introducing coagulant into the upper end of the outer tube at a volumetric rate such that the linear speed of coagulant between said tubes is less than about 1 meter per minute, and means for continuously collecting coagulant from the upper end of the 10 inner tube.

References Cited in the file of this patent UNITED STATES PATENTS 750,502 Thiele Jan. 26, 1904 15 6 Friedrich July 31, 1906 Hoffman Apr. 16, 1935 Dreyfus Aug. 6, 1940 Berndt Sept. 9, 1941 Sowter May 15, 1951 Tornonari June 16, 1953 Taylor Feb. 1, 1955 Lynch June 28, 1955 Tachikawa Ian. 24, 1956 Bradshaw et al. Jan. 31, 1956 Pedlow Dec. 25, 1956 FOREIGN PATENTS Great Britain Dec. 15, 1954 

1. APPARATUS FOR THE MANUFACTURE OF ARTIFICIAL FILAMENTARY MATERIAL BY WET SPINNING METHOD, WHICH COMPRISES A FIXED CLOSED VERTICAL OUTER TUBE, A FIXED COAXIAL NARROWER INNER TUBE HAVING NEAR ITS LOWER END VERTICAL FINS EXTENDING TO THE OUTER TUBE AND SERVING TO CENTER IT IN THE OUTER TUBE, SAID INER TUBE BEING CONSTRICTED AT ITS UPPER END AND FLARED OUTWARDLY AT ITS LOWER ENS AND OPENING INTO THE OUTER TUBE AT A LEVEL SUBSTANTIALLY ABOVE THE LOWER END OF THE OUTER TUBE AND EXTENDING UPWARD BEYOND THE UPPER END THEREOF, THE ARRANGEMENT BEING SUCH THAT LIQUID CAN FLOW DOWNWARDLY THROUGH THE ANNULAR SPACE BETWEEN THE TWO TUBES IN A SUBSTANTIALLY STREAMLINE MANNER, THE DIAMETER OF THE OUTER TUBE BEING AT LEAST THREE TIMES THAT OF THE INNER TUBE, AN UPWARDLY 